1. Field of the Invention
This invention relates to a coplanar line and an assembly installing the coplanar line.
2. Related Prior Art
An electrical and an optical package, in which a semiconductor device is assembled, have a coplanar line to connect the device with an outside of the package. The coplanar line comprises a signal line and ground planes disposed in both sides of the signal line. Since intervals between terminals of the semiconductor device is so narrow, for example smaller than a few hundred microns meters, the interval between the signal line and the ground plane must be formed in narrow to match the interval between the terminals of the semiconductor device. On the other hand in the outside of the package, the interval and the width thereof become a few millimeters to take the connection to the motherboard into account. Accordingly, it is necessary for the coplanar line to provide a portion where the width of the signal line and the distance to the ground plane vary gradually from the inside to the outside of the package.
The conventional coplanar line connecting the terminal with relatively narrower interval to that with relatively wider interval has a configuration that the straight line connects the both terminals. However, such configuration may degrade a transmitting characteristic of the signal line due to impedance mismatching of the signal line. One object of the present invention is to provide a coplanar line with a new configuration that suppresses degradation of signal transmission and to provide a module using such coplanar line.